Substrate processing method and substrate processing apparatus

ABSTRACT

A substrate (W) is processed with the use of a process liquid such as a deionized water. Then, a first fluid which is more volatile than the process liquid is supplied to an upper surface of the substrate (W) from a fluid nozzle ( 12 ) to form a liquid film. Next, a second fluid which is more volatile than the process liquid is supplied to the upper surface of the substrate (W) from the fluid nozzle ( 12 ), while the wafer (W) is being rotated. During this supply operation, a supply position (Sf) of the second fluid to the substrate (W) is moved radially outward from a rotational center (Po) of the substrate (W). As a result, it is possible to prevent the generation of particles on the substrate (W) after it is dried by using the first and second fluids.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a substrate processing method forcleaning substrates such as semiconductor wafers and then drying thesubstrates, and a substrate processing method therefor.

2. Background Art

When manufacturing a semiconductor device, a processing apparatus isused for cleaning, with the use of a chemical liquid, a semiconductorwafer (referred to as “wafer” below) held on a spin chuck. In a cleaningprocess performed by such an apparatus, a process liquid such as adeionized water is supplied to a wafer, and thereafter the wafer isrotated to remove liquid droplets therefrom due to the centrifugal forceso as to dry the wafer.

Conventional methods for drying a wafer include methods for spraying arotating wafer with an IPA (isopropyl alcohol) vapor, spraying arotating wafer with atomized IPA, and supplying an IPA liquid to arotating wafer. Another method for drying a wafer is, while supplying adeionized water to a wafer from a nozzle that radially moves outwardfrom a rotational center of the wafer, to supply an IPA vapor or thelike to the wafer at a position nearer to the rotational center than aposition at which the deionized water is supplied (JP 11-233481A, and JP2003-197590A).

However, when a wafer has a high hydrophobic property, the conventionalprocessing method is disadvantageous in that particles generate on asurface of the wafer after it is subjected to a drying process. Inparticular, when a wafer has a larger diameter, it is difficult torestrain particles (such as stripe water marks generated by aprecipitation of a chemical liquid or the like) from appearing near aperipheral portion of the wafer. A possible method for preventing thegeneration of such particles is to increase a supply amount of a dryingfluid such as IPA. However, a larger cost is required for the fluid.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a substrate processingmethod and a substrate processing apparatus capable of preventing thegeneration of particles on a substrate after it is dried, whiledecreasing the amount of fluid used for drying the substrate.

In order to achieve the above-described object, the present inventionprovides a substrate processing method comprising the steps of:

processing the substrate by a process liquid;

forming a liquid film on an upper surface of the substrate by supplyingthereon a first fluid having a higher volatility than that of theprocess liquid; and

supplying a second fluid having a higher volatility than that of theprocess liquid to the upper surface of the substrate, while rotating thesubstrate; wherein

at the step of supplying the second fluid, a supply position of thesecond fluid to the substrate is moved radially outward relative to arotational center of the substrate.

The substrate processing method may further comprise a chemical processstep of processing the substrate by a chemical liquid, before the stepof processing the substrate by the process liquid.

At the step of forming the liquid film, while rotating the substrate, asupply position of the first fluid to the substrate may be movedradially outward relative to the rotational center of the substrate toform the liquid film.

At the step of supplying the second fluid, a drying gas may be furthersupplied to the upper surface of the substrate, and supply positions ofthe drying gas and the second fluid to the substrate may be movedradially outward relative to the rotational center of the wafer,respectively, while maintaining the supply position of the drying gas tothe substrate nearer to the rotational center of the substrate than thesupply position of the second fluid.

The step of supplying the second fluid may be performed, while suckingan atmosphere near the upper surface of the substrate.

At least one of the step of forming the liquid film and the step ofsupplying the second fluid may be performed, with a humidity around thesubstrate being lower than that at the step of processing the substrateby the process liquid.

In addition, the present invention provides a storage medium for storinga program executable by a controller of a substrate processingapparatus, to execute a substrate processing method comprising the stepsof:

processing the substrate by a process liquid;

forming a liquid film on an upper surface of the substrate by supplyingthereon a first fluid having a higher volatility than that of theprocess liquid; and

supplying a second fluid having a higher volatility than that of theprocess liquid to the upper surface of the substrate, while rotating thesubstrate; wherein

at the step of supplying the second fluid, a supply position of thesecond fluid to the substrate is moved radially outward relative to arotational center of the substrate.

Moreover, the present invention provides a substrate processingapparatus comprising:

(a) a spin chuck configured to hold a substrate and rotate the same;

(b) a process liquid supply system configured to supply a process liquidto an upper surface of the substrate held by the spin chuck;

(c) a first fluid supply system having a first fluid nozzle, configuredto supply, from the first fluid nozzle to the upper surface of thesubstrate, a first fluid having a higher volatility than that of theprocess liquid;

(d) a second fluid supply system having a second fluid nozzle,configured to supply, from the second fluid nozzle to the upper surfaceof the substrate, a second fluid having a higher volatility than that ofthe process liquid;

(e) a nozzle moving mechanism configured to move radially outward thesecond fluid nozzle relative to a rotational center of the substrate;and

(f) a controller configured to control the spin chuck, the processliquid supply system, the first fluid supply system, the second fluidsupply system, and the nozzle moving mechanism, to execute the steps of:

supplying the process liquid from the supply system to the upper surfaceof the substrate;

supplying the first fluid from the first fluid nozzle to the uppersurface of the substrate; and

supplying the second fluid from the second fluid nozzle to the uppersurface of the substrate, while rotating the substrate by the spin chuckand moving the second fluid nozzle by the nozzle moving mechanism.

The substrate processing apparatus may further comprise a drying gasnozzle configured to supply a drying gas to the upper surface of thesubstrate; wherein

the nozzle moving mechanism is configured to move radially outward thedrying gas nozzle and the second fluid nozzle relative to the rotationalcenter of the substrate, while maintaining the drying gas nozzle nearerto the rotational center of the substrate than the second fluid nozzle.

The substrate processing apparatus may further comprise a suction nozzleconfigured to suck an atmosphere near the upper surface of thesubstrate, wherein

the nozzle moving mechanism is configured to move radially outward thesuction nozzle and the second fluid nozzle relative to the rotationalcenter of the substrate, while maintaining the suction nozzle fartheraway from the rotational center of the substrate than the second fluidnozzle.

The substrate processing apparatus may further comprise a humidityadjusting system configured to adjust a humidity around the substrateheld by the spin chuck.

For example, the drying gas is an inert gas or a dry air. For example,the processing liquid is a rising liquid, such as a deionized water. Forexample, at least one of the first liquid and the second liquid isselected from the group consisting of an IPA liquid, an IPA solution, amist of IPA liquid, an IPA vapor, and a vapor of IPA solution. That is,the “fluid having a higher volatility than that of the process liquid”in the present invention is a concept including a liquid having a highervolatility than that of the process liquid, and a vapor of such liquid.

According to the present invention, a first fluid having a highervolatility than that of a process liquid is supplied to an upper surfaceof a substrate to form thereon a liquid film, at first. Then, a secondfluid having a higher volatility than that of the process liquid issupplied to the upper surface of the substrate, while the substrate isbeing rotated. During this supply operation, a supply position of thesecond fluid is moved radially outward relative to a rotational centerof the substrate. Due to this, it is possible to prevent the generationof particles on the substrate after it is dried by using the first andsecond fluids.

When the second fluid is supplied, a drying gas is supplied to the uppersurface of the substrate, and a supply position of the drying gas andthe supply position of the second fluid are moved radially outwardrelative to the rotational center of the substrate, while maintainingthe supply position of the drying gas to the substrate nearer to therotational center of the substrate than the supply position of thesecond fluid to the substrate. Since the use of the drying gas promotesdrying of the substrate, an amount of the second fluid used for dryingthe substrate can be relatively reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of one embodiment of a substrate processingapparatus according to the present invention;

FIG. 2 is a horizontal cross-sectional view of a main part of thesubstrate processing apparatus shown in FIG. 1;

FIG. 3 is a perspective view of assistance in explaining an arrangementof a fluid nozzle at a liquid film forming step of the substrateprocessing apparatus shown in FIG. 1;

FIG. 4 is a perspective view of assistance in explaining actions of afluid nozzle and a drying gas nozzle at a drying step of the substrateprocessing apparatus shown in FIG. 1;

FIG. 5 is a plan view of assistance in explaining an arrangement of afluid nozzle and a drying gas nozzle of another embodiment of thesubstrate processing apparatus according to the present invention;

FIG. 6 is a perspective view of assistance in explaining openingdimensions (shapes) of a fluid nozzle and an inert-gas nozzle of anotherembodiment of the substrate processing apparatus according to thepresent invention;

FIG. 7 is a schematic view of another embodiment of the substrateprocessing apparatus according to the present invention, that isprovided with a fluid heater and a drying gas heater;

FIG. 8 is a perspective view of assistance in explaining actions of asuction nozzle, a fluid nozzle, and a drying gas nozzle, of anotherembodiment of the substrate processing apparatus according to thepresent invention;

FIG. 9 is a plan view of assistance in explaining an arrangement of asuction nozzle, a fluid nozzle, and a drying gas nozzle, of anotherembodiment of the substrate processing apparatus according to thepresent invention;

FIG. 10 is a perspective view of assistance in explaining actions of afluid nozzle and a drying gas nozzle at a drying step of anotherembodiment of the substrate processing apparatus according to thepresent invention;

FIG. 11 is a schematic view of another embodiment of the substrateprocessing apparatus according to the present invention, that isprovided with a moisture adjusting system; and

FIG. 12 is a schematic view of another embodiment of the substrateprocessing apparatus according to the present invention, that isprovided with a moisture adjusting system.

DETAILED DESCRIPTION OF THE INVENTION

Preferred embodiments of the present invention will be described below,based on a substrate processing apparatus for cleaning an upper surfaceof a substantially disk-shaped silicon wafer W as a substrate.

As shown in FIG. 1, a substrate processing apparatus 1 in thisembodiment includes a process vessel 2 in which a spin chuck 3 isdisposed to substantially horizontally hold the wafer W and rotate thesame. A liquid nozzle 5 is disposed for supplying to the wafer W acleaning chemical liquid, such as DHF (dilute hydrofluoric acid), and arinse liquid such as a deionized water (DIW). The liquid nozzle 5 issupported by a first support arm 6. A fluid nozzle 12 is disposed tosupply, as a first fluid and a second fluid, a fluid having a highervolatility than that of a deionized water as a rinse liquid, such as anIPA (isopropyl alcohol) liquid. A drying gas nozzle 13 is disposed tosupply, as a drying gas, an inert gas such as nitrogen gas (N₂ gas). Thefluid nozzle 12 and the drying gas nozzle 13 are supported by a secondsupport arm 15. A controller 16 including a CPU is disposed to controlthe respective elements of the substrate processing apparatus 1.

As shown in FIG. 2, a loading/unloading port 17 is disposed in theprocess vessel 2 through which the wafer W is loaded into an insideprocessing space S and is unloaded therefrom. By closing theloading/unloading port 17, it is possible to hermetically seal theprocessing space S.

As shown in FIGS. 1 and 2, three holding members 18 are disposed abovethe spin chuck 3. The holding members 18 are adapted to be in contactwith a periphery of the wafer W at three points so as to substantiallyhorizontally hold the wafer W. A motor 20 is disposed below the spinchuck 3 to rotate the same through a vertical rotational shaft. When thespin chuck 3 is rotated by the motor 20, the wafer W together with thespin chuck 3 is rotated in a horizontal plane about a center Po of thewafer W. Driving of the motor 20 is controlled by the controller 16.

The first support arm 6 is disposed above the wafer W supported by thespin chuck 3. A proximal end of the support arm 6 is supported to becapable of moving along a guide rail 31 which is substantiallyhorizontally placed. A driving mechanism 32 is disposed for moving thesupport arm 6 along the guide rail 31. As shown in FIG. 2, along with amovement of the support arm 6 which is driven by the driving mechanism32, the liquid nozzle 5 can radially move outside the wafer W relativeto the rotational center Po of the wafer W. Driving of the drivingmechanism 32 is controlled by the controller 16 (FIG. 1).

As shown in FIG. 1, the liquid nozzle 5 is attached to a lower end of anelevating shaft 36 extending downward from an elevating mechanism 35fixed on a distal end of the support arm 6. The elevating shaft 36 iscapable of vertically moving by the elevating mechanism 35, such that aposition of the liquid nozzle 5 is set at a given height. Driving of theelevating mechanism 35 is controlled by the controller 16.

The liquid nozzle 5 is connected to a chemical liquid (DHF) supplysource 41 through a chemical liquid supply channel 42, and is connectedto a rinse liquid (DIW) supply source 43 through a rinse liquid supplychannel 44. On-off valves 45 and 46 are disposed on the chemical liquidsupply channel 42 and the rinse liquid supply channel 44, respectively.On-off actions of the on-off valves 45 and 46 are controlled by thecontroller 16. The liquid nozzle 5, the chemical liquid supply source41, the chemical liquid supply channel 42, and the on-off valve 45constitute a chemical liquid supply system. The liquid nozzle 5, therinse liquid supply source 43, the rinse liquid supply channel 44, andthe on-off valve 46 constitute a rinse liquid (process liquid) supplysystem.

The second support arm 15 is disposed above the wafer W supported by thespin chuck 3. A proximal end of the support arm 15 is supported to becapable of moving along a guide rail 51 which is substantiallyhorizontally placed. A driving mechanism 52 is disposed for moving thesupport arm 15 along the guide rail 51. These members constitutes anozzle moving mechanism that horizontally moves the fluid nozzle 12 andthe drying gas nozzle 13. As shown in FIG. 2, along with the movement ofthe support arm 15 which is driven by the driving mechanism 52, thefluid nozzle 12 and the drying gas nozzle 13 can radially move outsidethe wafer W relative to the rotational center Po of the wafer W. Drivingof the driving mechanism 52 is controlled by the controller 16 (FIG. 1).

As shown in FIG. 1, an elevating mechanism 55 provided with an elevatingshaft 54 is fixed on a distal end of the second support arm 15. Theelevating shaft 54 extends downward from the elevating mechanism 55. Thefluid nozzle 12 and the drying gas nozzle 13 are attached to a lower endof the elevating shaft 54. The elevating shaft 54 is driven by theelevating mechanism 55 to expand and contract, so that the fluid nozzle12 and the drying gas nozzle 13 are vertically moved together. Drivingof the elevating mechanism 55 is controlled by the controller 16. Thatis, based on instructions from the controller 16, driving of the drivingmechanism 52 is controlled so as to move the support arm 15, the fluidnozzle 12, and the drying gas nozzle 13 in the horizontal direction(nozzle moving direction D), while driving of the elevating mechanism 55is controlled so as to adjust positions of the fluid nozzle 12 and thedrying gas nozzle 13 in the vertical direction.

As shown in FIGS. 3 and 4, the fluid nozzle 12 and the drying gas nozzle13 are adjacently aligned in the radial direction (nozzle movingdirection D) opposite the liquid nozzle 5 relative to the rotationalcenter Po of the wafer W. That is, the drying gas nozzle 13 ispositioned nearer to the rotational center Po of the wafer W than thefluid nozzle 12 in the nozzle moving direction D (strictly speaking,under conditions that a distance between a radial position of the fluidnozzle 12 and the rotational center Po is shorter than a distancebetween the nozzles 12 and 13 (see, FIG. 3), the positional relationshipbetween the nozzles 12 and 13 is inverted).

The fluid nozzle 12 is connected through a fluid supply channel 67 to afluid supply source 66, such as a tank, in which an IPA liquid isreceived. An on-off valve 68 is disposed on the fluid supply channel 67.An on-off action of the on-off valve 68 is controlled by the controller16. The fluid nozzle 12, the fluid supply source 66, the fluid supplychannel 67, and the on-off valve 68 constitute a fluid supply system.

The drying gas nozzle 13 is connected to an inert gas (N₂) supply source71 through an inert gas supply channel 72. An on-off valve 73 isdisposed on the inert gas supply channel 72. An on-off action of theon-off valve 73 is controlled by the controller 16. The gas nozzle 13,the gas supply source 71, the gas supply channel 72, and the on-offvalve 73 constitute a drying gas supply system.

Respective functional elements in the substrate processing apparatus 1are connected through signal lines to the controller that automaticallycontrols an overall operation of the substrate processing apparatus 1.The functional elements herein mean all the elements, such as the motor20, the driving mechanism 32, the elevating mechanism 35, the drivingmechanism 52, the elevating mechanism 55, and the on-off valves 45, 46,68, and 73, that are operated to execute predetermined processes. Thecontroller 16 is typically a multi-purpose computer capable of realizinga given function depending on a program to be executed.

As shown in FIG. 1, the controller 16 includes an operating part 16 aprovided with a CPU (central processing unit), an input/output part 16 bconnected to the operating part 16 a, and a storage medium 16 c storinga control program that is read out through the input/output part 16 b.The storage medium 16 c stores therein a control program to be executedby the controller for executing steps of the below-described substrateprocessing method by the substrate processing apparatus 1. Thecontroller 16 executes the control program to control the respectivefunctional elements in the substrate processing apparatus 1, such thatvarious processing conditions (for example, a rotational speed of themotor 20) defined by a predetermined processing recipe are achieved. Inthe substrate processing method based on the control program, a chemicalprocess step, a rinsing step, a liquid film forming step, and a dryingstep are sequentially executed, which will be described in detail below.

The storage medium 16 c may be fixedly disposed on the controller 16.Alternatively, the storage medium 16 c may be removably disposed on areader, not shown, mounted on the controller 16, and may be readable bythe reader. In the most typical case, the storage medium 16 c is a harddisk drive in which a control program has been installed by an operatorof a manufacturing company of the substrate processing apparatus 1. Inanother case, the storage medium 16 c is a removable disk such as CD-ROMor DVD-ROM in which a control program is written. Such a removable diskis read by a not-shown optical reader mounted on the controller 16. Thestorage medium 16 c may either be a RAM (random access memory) type or aROM (read only memory) type. Alternatively, the storage medium 16 c maybe a cassette type ROM. In short, any medium known in the technicalfield of a computer can be employed as the storage medium 16 c. In afactory where the plurality of substrate processing apparatuses 1 areplaced, the control program may be stored in an executive computer thatcomprehensively controls the controller 16 in each substrate processingapparatus 1. In this case, the respective substrate processingapparatuses 1 are operated by the executive controller via communicationlines so as to execute predetermined processes.

Now, a method for processing a wafer W carried out by the substrateprocessing apparatus 1 as structured above is described.

First, a wafer W, which has not been cleaned yet, is loaded into theprocess vessel 2 by a transfer arm, not shown, and the wafer W is heldby the spin chuck 3 as shown in FIG. 1. In order to deliver the wafer Wto the spin chuck 3, as indicated by the two-dot chain lines shown inFIG. 2, the first and the second support arms 6 and 15 are previouslyretracted to standby positions located outside the spin chuck 3.

After the wafer W is held by the spin chuck 3, the spin chuck 3 isdriven in rotation by the motor 20 shown in FIG. 1 to start a rotationof the wafer W. Then, the chemical process step is started. First, asindicated by the chain lines shown in FIG. 2, the first support arm 6 ismoved such that the liquid nozzle 5 is positioned above the rotationalcenter Po of the wafer W. Then, a chemical liquid is supplied from theliquid nozzle 5 toward the rotational center Po of the wafer W. Thechemical liquid supplied to the rotational center Po is dispersed overthe whole upper surface of the wafer W due to the centrifugal force.Thus, a liquid film of the chemical liquid is formed on the uppersurface of the wafer W. A rotational speed of the wafer W while thechemical liquid is supplied thereto is set at about 500 rpm. After theliquid film of the chemical liquid is formed, the supply of the chemicalliquid from the liquid nozzle 5 is stopped. Thereafter, by leaving thewafer W as it is for a predetermined period of time, the upper surfaceof the wafer W is processed by the liquid film of the chemical liquid. Ahydrophobic property of the upper surface of the wafer W is increased bythis chemical process.

Upon completion of the chemical process, the rinsing step is performed.In the rinsing step, a deionized water is supplied toward the rotationalcenter Po of the rotating wafer W from the liquid nozzle 5. The thussupplied deionized water is dispersed over the whole upper surface ofthe wafer W due to the centrifugal force. The chemical liquid adhered tothe upper surface of the wafer W is rinsed away from the wafer W by thedeionized water. A rotational speed of the wafer W during the rinsingprocess is preferably faster than that of the wafer W while the chemicalliquid is supplied thereto, and is set at about 1000 rpm, for example.After the wafer W is sufficiently rinsed by the deionized water, thesupply of the deionized water from the liquid nozzle 5 is stopped.Thereafter, the support arm 6 positioned above the wafer W is retractedtherefrom to be returned to the standby position.

Following the rinsing step, a liquid film forming step is carried outfor forming a liquid film of an IPA liquid on the wafer W. First, asindicated by the chain lines shown in FIG. 2, the second support arm 15is moved such that the fluid nozzle 12 is positioned above therotational center Po of the wafer W. Then, as shown in FIG. 3, an IPAliquid (first fluid) is supplied from the fluid nozzle 12 toward therotational center Po of the wafer W that is rotated at a predeterminedrotational speed. The thus supplied IPA liquid is dispersed over thewhole upper surface of the wafer W due to the centrifugal force, and aliquid film of the IPA liquid is formed on the whole upper surface ofthe wafer W. Formation of the liquid film can ensure that the deionizedwater adhered to the wafer W is brought in and mixed with the IPA liquidon the whole upper surface of the wafer W. In addition, the uppersurface of the wafer W can be prevented from drying. A rotational speedof the wafer W during the liquid film forming step is preferably slowerthan that of the wafer W during the rinsing process, and is set at about300 rpm, for example.

After the liquid film of the IPA liquid is formed on the upper surfaceof the wafer W, a drying step for drying the wafer W is performed bysupplying an IPA liquid (second fluid) and nitrogen gas (drying gas) tothe wafer W. First, a supply of an IPA liquid from the fluid nozzle 12and then a supply of nitrogen gas from the drying gas nozzle 13 arestarted, with the fluid nozzle 12 and the drying gas nozzle 13 beingpositioned near above the rotational center Po of the wafer W. Then, asshown in FIG. 4, the second support arm 15 is moved in the nozzle movingdirection D, while continuing to supply the IPA liquid and the nitrogengas from the nozzles 12 and 13 to the upper surface of the rotatingwafer W. Thus, as shown in FIG. 4, a supply position Sf of the IPAliquid supplied from the fluid nozzle 12 to the upper surface of thewafer, and a supply position Sn of the nitrogen gas supplied from thedrying gas nozzle 13 to the upper surface of the wafer, are movedradially outward from the rotational center Po of the wafer W. Since thewafer W is rotated, the IPA liquid and the nitrogen gas can be suppliedover the whole upper surface of the wafer W.

The supply of the IPA liquid and the supply of the nitrogen gas may besimultaneously started. For example, by starting the supply of the IPAliquid and the nitrogen gas when the fluid nozzle 12 is moved to aposition directly above the rotational center Po of the wafer W, thesupply of the IPA liquid may be started from the rotational center Po ofthe wafer W, and the supply of the nitrogen gas may be started from aposition slightly behind away from the rotational center Po in thenozzle moving direction D. Alternatively, the supply of the nitrogen gasmay be started, after starting the supply of the IPA liquid, when thedrying gas nozzle 13 is moved to a position directly above therotational center Po of the wafer W, whereby the supply of the nitrogengas is started from the rotational center Po of the wafer W.Alternatively, the supply of the IPA liquid and the supply of thenitrogen gas may be started at positions slightly behind away from therotational center Po in the nozzle moving direction D.

The IPA liquid supplied on the upper surface of the rotating wafer Wflows radially outward on the wafer W due to the centrifugal force.While the supply position Sf of the IPA liquid is moved in the nozzlemoving direction D, the supply position Sn of the drying gas ismaintained nearer to the rotational center Po of the wafer W than theadjacent supply position Sf. In this case, the supply position Sn of thenitrogen gas is positioned between the rotational center Po and thesupply position Sf. Thus, the IPA liquid supplied onto the upper surfaceof the wafer W is immediately washed away by the nitrogen gas, so thatdrying of the wafer W can be expedited. Accordingly, the wafer W can beefficiently dried with a less amount of IPA liquid, i.e., an amount ofIPA liquid to be used can be restrained. Further, since an oxidationdensity causing water marks can be suppressed, the generation of watermarks can be avoided.

A rotational speed of the wafer W at the drying step is between about500 rpm and 800 rpm, for example. A moving speed of the supply positionSf of the IPA liquid and the supply position Sn of the nitrogen gas inthe moving direction D is, e.g., about 150 mm/sec. Alternatively, arotational speed of the wafer W may be varied in accordance with radiallocations of the supply positions Sf and Sn on the wafer W. For example,when the supply positions Sf and Sn reside radially inward in the waferW, the rotational speed of the wafer W may be increased. Meanwhile, whenthe supply positions Sf and Sn reside radially outward in the wafer W,the rotational speed of the wafer W may be lowered. To give an actualexample, in drying the wafer W with a diameter of about 300 mm, thewafer W may be driven at a rotational speed of 800 rpm when the supplypositions Sf and Sn are located within a radius of about 90 mm from therotational center Po of the wafer W. Meanwhile, the wafer W may bedriven at a rotational speed of 500 rpm, when the supply positions Sfand Sn are located outside the above range.

Alternatively, a moving speed of the supply positions Sf and Sn in thenozzle moving direction D may be varied in accordance with radiallocations of the supply positions Sf and Sn on the wafer W. For example,when the supply positions Sf and Sn reside radially inward in the waferW, the moving speed thereof may be increased. Meanwhile, when the supplypositions Sf and Sn reside radially outward in the wafer W, the movingspeed thereof may be lowered. To give an actual example, in drying thewafer W with a diameter of about 300 mm, the supply positions Sf and Snmay be moved at a moving speed of about 7 mm/sec, when the supplypositions Sf and Sn are located within a radius of about 90 mm from therotational center Po of the wafer W. Meanwhile, the supply positions Sfand Sn may be moved at a moving speed of about 3 mm/sec, when the supplypositions Sf and Sn are outside the above range.

When the supply position Sf of the IPA liquid reaches a position on aperiphery of the wafer W, the supply of the IPA liquid from the fluidnozzle 12 is stopped. Similarly, when the supply position Sn of thenitrogen gas reaches a position on the periphery of the wafer W, thesupply of the nitrogen gas from the drying gas nozzle 13 is stopped.Then, the drying step is completed. It is possible to temporarily staythe supply position Sn of the nitrogen gas at a position on theperiphery of the wafer W to continue for a while the supply of thenitrogen gas onto the periphery, and then stop the supply of thenitrogen gas. In this case, the wafer can be more reliably dried.

After the drying step is finished, the rotation of the spin chuck 3 isstopped, and the not-shown transfer arm is allowed to enter the processvessel 2. The wafer W is delivered from the spin chuck 3 to the transferarm, and is then unloaded from the process vessel 2. In this manner, aseries of processes for the wafer W performed by the substrateprocessing apparatus 1 are finished.

As described above, according to this embodiment, after the deionizedwater is supplied, a liquid film of the IPA liquid (first fluid) isformed on the upper surface of the wafer W. Thus, the deionized wateradhered to the upper surface of the wafer W can be surely brought in andmixed with the IPA liquid. In addition, since the liquid film coveringthe wafer W prevents a natural drying of the upper surface of the waferW, in particular, a periphery thereof, the generation of particles onthe upper surface of the wafer W can be prevented. Even when the uppersurface of the wafer W is highly hydrophobic, the generation ofparticles can be efficiently prevented.

After the liquid film of the IPA liquid is formed, the IPA liquid(second fluid) is supplied to the wafer W, while the supply position Sfis moved radially outward from the rotational center Po, i.e., in themoving direction D. Thus, the liquid film of the IPA liquid (firstfluid) taking therein and being mixed with the deionized water can beflushed away and removed from the wafer W. As a result, the uppersurface of the wafer W can be uniformly, efficiently dried. In addition,nitrogen gas for drying the wafer W is supplied at the supply positionSn, which is behind the supply position Sf of the IPA liquid in themoving direction D, so that the liquid (mainly the IPA liquid) remainingon the wafer W is washed out toward the periphery of the wafer W. Thus,drying of the wafer W can be promoted. Accordingly, an amount of the IPAliquid (second fluid) used for drying the wafer W can be relativelyreduced. Besides, the generation of particles caused by a differencebetween a volatile property of IPA and that of a deionized water can beprevented to thereby enhance a quality of the wafer W.

Although the preferred embodiment of the present invention has beendescribed, the present invention is not limited to the above embodiment.For example, not limited to a semiconductor wafer, a substrate may be aglass substrate for an LCD, a CD substrate, a print substrate, a ceramicsubstrate, and so on.

The method has been described in which the wafer W is subjected to thechemical process step, the rinsing step, the liquid film forming step,and the drying step. However, the present invention is not limitedthereto, and can be applied to various other processes. Besides, achemical liquid used in the chemical process step is not limited to aliquid for cleaning the wafer W. For example, the chemical process stepmay be an etching step in which the wafer W is etched by supplyingthereto an etching chemical liquid, such as HF (hydrogen fluoride).Alternatively, the chemical process step may be a step for removing aresist, and a step for removing etching residues. Moreover, the wafer Wmay subjected to, for example, a scrubbing process in which the wafer Wis rubbed by a scriber such as a brush and a sponge, and subsequentlysubjected to the rinsing step, liquid film forming step, and dryingstep. Although a deionized water as a rinse liquid is given as anexample of a process liquid, the process liquid is not limited thereto.

In the above embodiment, the chemical liquid and the rinse liquid(process liquid) are supplied from the same liquid nozzle 5. However,these liquids may naturally be supplied from separate nozzles. In thiscase, a nozzle for supplying the chemical liquid and a nozzle forsupplying the rinse liquid may be respectively supported by separatearms. Alternatively, the nozzle for supplying the rinse liquid may besupported by the support arm 15 that supports the fluid nozzle 12 andthe drying gas nozzle 13.

Given herein as an example to describe the liquid film forming step is acase in which the IPA liquid (first fluid) is supplied onto therotational center Po of the wafer W, and a liquid film is formed byutilizing the centrifugal force caused by the rotation of the wafer W.However, a method for forming a liquid film is not limited thereto. Forexample, the supply position of the IPA liquid may be moved above thewafer W between the rotational center Po and the periphery of the waferW, while rotating the wafer W. In this case as well, a liquid film canbe suitably formed. In this method, the supply position of the IPAliquid may either be radially moved only once in an outward or inwarddirection relative to the rotational center Po, or be radiallyreciprocated once or more relative to the rotational center Po. A movingspeed of a supply position of the IPA liquid (first fluid) at the liquidfilm forming step is preferably faster than that of the supply positionSf of the IPA liquid (second fluid) at the drying step. This enablesthat a liquid film is formed more rapidly. At the liquid film formingstep, a moving speed of the supply position of the IPA liquid is, e.g.,about 150 mm/sec, and a rotational speed of the wafer W is e.g., about300 rpm. The rotational speed of the wafer W at the liquid film formingstep is preferably slower than that of the wafer W at the drying step.This enables a reliable formation of a liquid film, without thecentrifugal force discouraging the liquid film formation. On the otherhand, since the wafer W is rotated at relatively a higher speed, thewafer W can be promptly dried.

The first and second fluids, that have a volatile property higher thanthe rinse liquid (process liquid), are not limited to an IPA liquid.Instead of the IPA liquid, an IPA solution containing IPA diluted by adeionized water or the like may be used as at least one of the first andsecond fluids (hereinafter referred to as “drying fluid”). In this case,an amount of the drying fluid to be used can be reduced, which resultsin decrease in cost. In addition to a liquid state, the drying fluid maytake an atomized state, a jet-flow state, and a gaseous state. Forexample, a mist of IPA liquid, a mist of IPA solution, an IPA vapor, ora vapor of IPA solution (mixed vapor in which IPA vapor and water vaporare mixed) may be used as the drying fluid. Besides, a mixture of themist or vapor and a gas such as nitrogen gas may be used as the dryingfluid. Moreover, an organic solvent containing an organic compound suchas HFE (hydrofluoro ether) and acetone, and a liquid containing asurface-active agent may be used as the drying fluid. In this case, anystate, such as an atomized state, a jet-flow state, and a vapor state,will do. Also in the case where these fluids are used as the secondfluid, drying of the wafer W can be accelerated by simultaneouslysupplying a drying gas such as nitrogen gas. Thus, an amount of thesecond fluid to be used can be decreased, so that a reduction in costcan be achieved.

Alternatively, the first fluid and the second fluid may not be identicalto each other. For example, a density of IPA in an IPA solution used asthe first fluid and a density of IPA in an IPA solution used as thesecond fluid may be different from each other. Alternatively, states(phases) of the first fluid and the second fluid may be different fromeach other. For example, it is possible to use a liquid such as an IPAliquid as the first fluid, and to use a gas such as an IPA vapor or amist of IPA liquid as the second fluid.

In the above embodiment, although the first fluid and the second fluidare supplied from the single fluid nozzle 12, the first fluid and thesecond fluid may be supplied from separate nozzles. For example, a firstnozzle for supplying the first fluid and a second fluid nozzle forsupplying the second fluid may be supported by the support arm 15 so asto move the first fluid nozzle, the second fluid nozzle, and the dryinggas nozzle 13 all together.

A two-fluid nozzle may be used as a nozzle for supplying the dryingfluid. For example, an IPA liquid or IPA solution is formed inside thetwo-fluid nozzle into a jet-flow of a number of particulate droplets bymixing a liquid, such as an IPA liquid or IPA solution, and a gas, suchas nitrogen gas. The droplets are accelerated by the gas and jetted fromthe two-fluid nozzle. A structure of the two-fluid nozzle is not limitedto an internal mixing type, but may be a structure of an external mixingtype in which a liquid and a gas are mixed outside.

Another embodiment of the substrate processing apparatus shown in FIG. 5is described below. In this embodiment, a supply position Sn of nitrogengas (drying gas nozzle 13) to a wafer W is positioned ahead of a supplyposition Sf of an IPA liquid (second fluid) (fluid nozzle 12) to thewafer W, in a rotational direction (CCW) of the wafer W. In FIG. 5, asupply area of the IPA liquid from the nozzle 12 is depicted by a circleAf indicated by the broken line, and a supply area of the nitrogen gasfrom the nozzle 13 is depicted by a circle An indicated by the brokenline. A center point of the supply area Af is represented by the supplyposition Sf, and a center point of the supply area An is represented bythe supply position Sn. A line Lf connects the supply position Sf andthe rotational center Po of the wafer W to each other. A line Lnconnects the supply position Sn and the rotational center Po of thewafer W to each other. In this case, the line Ln is displaced from theline Lf at an angle θn which is smaller than 90° in the rotationaldirection of the wafer W. Thus, the nitrogen gas (drying gas) followingthe IPA liquid (second fluid) can be constantly supplied to the wafer Wnot only in the radial direction but also in the rotational direction ofthe wafer W. Therefore, the wafer W can be rapidly dried by flushingaway the IPA liquid on the wafer W away by the drying gas.

Another embodiment of the substrate processing apparatus shown in FIG. 6is described below. In this embodiment, opening dimension Bn of a dryinggas nozzle 13 is larger than opening dimension Bf of a fluid nozzle 12,in a direction perpendicular to a nozzle moving direction D (herein, thedirection is in parallel to a surface of a wafer W). To be specific, thefluid nozzle 12 has a circular opening 12 a, while the drying gas nozzle13 has a rectangular opening 13 a whose long side is longer than adiameter of the circular opening 12 a. Thus, dimension of a supply areaAn of the drying gas is larger than dimension of a supply area Af of asecond fluid (IPA liquid, for example), in the direction perpendicularto the nozzle moving direction D. This design enables that nitrogen gascan be sufficiently supplied at a position behind the supply position Sfin the moving direction D, so that the IPA liquid can be efficientlywashed away by the nitrogen gas. Therefore, the wafer W can beefficiently, reliably dried.

Not limited to nitrogen gas, a drying gas used at the drying step may beanother inert gas. The drying gas is not limited to an inert gas, butmay be air or the like. Also in this case, the second fluid (e.g., IPAliquid) which has been supplied on an upper surface of the wafer W canbe flushed away, and drying of the wafer W can be promoted. In addition,the drying gas may be a gas, such as a dry air or the like, with itshumidity being forcibly lowered as compared with a general state of thegas. In this case, a humidity near the upper surface of the wafer W canbe reduced to facilitate evaporation of a liquid, such as the IPAliquid, adhered to the wafer W, whereby drying of the wafer W can bemore expedited. An absolute humidity of the drying gas is not more than1 g/m³, for example.

Next, another embodiment of the substrate processing apparatus shown inFIG. 7 is described below. In this embodiment, there are furtherprovided a fluid heater 67 a that heats a second fluid (IPA liquid orthe like) to be supplied from a fluid nozzle 12, and a drying gas heater72 a that heats a drying gas to be supplied from a drying gas nozzle 13.The fluid heater 67 a is disposed on a fluid supply channel 67, and iscontrolled by a controller 16. The drying gas heater 72 a is disposed onan inert gas supply channel 72, and is controlled by the controller 16.The fluid heater 67 a may be disposed on a tank of a fluid supply source66.

To supply from the fluid nozzle 12 a second fluid forcibly heated by thefluid heater 67 a at a temperature higher than a normal temperaturepromotes evaporation of the first fluid and the second fluid that havebeen supplied to the wafer W, whereby the wafer W can be moreefficiently dried. Similarly, to supply from the drying gas nozzle 13 adrying gas forcibly heated at a temperature higher than a normaltemperature promotes evaporation of the first fluid and the second fluidthat have been supplied to the wafer W, whereby the wafer W can be moreefficiently dried.

Another embodiment of the substrate processing apparatus shown in FIG. 8is described below. In this embodiment, there is further provided asuction nozzle 80 that sucks an atmosphere near an upper surface of awafer W. To be specific, the suction nozzle 80 provided with a suctionopening 80 a is disposed on a support arm 15 such that the suctionnozzle 80 is moved together with a fluid nozzle 12 and a drying gasnozzle 13. In this case, while a supply position Sf (fluid nozzle 12) ofa second fluid is moved in a nozzle moving direction D, the suctionopening 80 a of the suction nozzle 80 is maintained farther away from arotational center Po of the wafer W than the adjacent supply position Sfof an IPA liquid. A suction apparatus such as a pump, not shown, isconnected the suction nozzle 80. An actuation of the suction apparatusis controlled by a controller 16, and a suction action by the suctionnozzle 80 is controlled.

Due to this structure, at the drying step, moisture contained in anatmosphere near the supply position Sf can be sucked by the suctionnozzle 80, while the second fluid (IPA liquid or the like) is suppliedfrom the fluid nozzle 12 which is moved in the moving direction D. Thus,it can be prevented that moisture in the processing space S is dissolvedin the second fluid supplied onto the supply position Sf on the wafer W.Therefore, the wafer W can be favorably dried. In particular, by suckingan atmosphere at a position ahead of the supply position Sf of thesecond fluid in the moving direction D, an more improved effect can beobtained.

Another embodiment of the substrate processing apparatus shown in FIG. 9is described below. In this embodiment, a center point of the suctionopening 80 a of the suction nozzle 80 relative to the wafer W in theembodiment shown in FIG. 8 is positioned ahead of a supply position Sf(fluid nozzle 12) of a second fluid (IPA liquid or the like) to thewafer W, in a rotational direction (CCW) of the wafer W. In FIG. 9,similar to FIG. 5, a supply area of the second fluid from the nozzle 12is depicted by a circle Af indicated by the broken line, and a supplyarea of a drying gas from a nozzle 13 is depicted by a circle Anindicated by the broken line. A center point of the supply area Af isrepresented by a supply position Sf, and a center point of the supplyarea An is represented by a supply position Sn. A line Lf connects thesupply position Sf of the second fluid and a rotational center Po of thewafer W to each other. A line La connects the supply position Sn and therotational center Po of the wafer W to each other. In this case, theline La is displaced from the line Lf at an angle θa which is smallerthan 90° in the rotational direction of the wafer W. Thus, the precedingsuction opening 80 a can suck an atmosphere above the wafer W, justbefore the second fluid is supplied to an upper surface of the wafer Wfrom the fluid nozzle 12. Therefore, it can be effectively preventedthat moisture in a processing space S is dissolve in the IPA liquidsupplied to the wafer W.

In this embodiment, the fluid nozzle 12 and the drying gas nozzle 13 aresupported by a sole support arm 15, such that the fluid nozzle 12 andthe drying gas nozzle 13 are moved together with the support arm 15.However, the fluid nozzle 12 and the drying gas nozzle 13 may besupported by separate support arms.

In this embodiment, while the second fluid is supplied to the wafer W,the fluid nozzle 12 and the drying gas nozzle 13 are moved in the samedirection relative to the wafer W, i.e., in the moving direction D.However, the fluid nozzle 12 and the drying gas nozzle 13 may be movedin different directions.

Another embodiment of the substrate processing apparatus shown in FIG.10 is described below. In this embodiment, a fluid nozzle 12 and adrying gas nozzle 13 are respectively supported by separate supportarms, which structure is different from the embodiment shown in FIGS. 1to 4. In this embodiment, the fluid nozzle 12 and the drying gas nozzle13 are radially moved in different directions. To be specific, there areseparately disposed a support arm that supports the fluid nozzle 12 anda support arm that supports the drying gas nozzle 13. At the dryingstep, the respective support arms are radially moved in differentdirections at an angle of 180° by a control of a controller 16 (FIG. 1).Thus, the fluid nozzle 12 and the drying gas nozzle 13 are movedradially outward in different directions at an angle of 180° from arotational center Po of the wafer W. Also in this case, a supplyposition Sn of a drying gas is maintained at a position nearer to therotational center Po of the wafer W than a supply position Sf of asecond fluid. That is, a distance between the supply position Sn of adrying gas and the rotational center Po is controlled to be constantlyshorter than a distance between the supply position Sf of a second fluidand the rotational center Po. Also in this case, with a rotation of thewafer W to move the second fluid which has been supplied at the supplyposition Sf in an upper surface of the wafer W toward the supplyposition Sn of a drying gas, the second fluid is blown off toward anouter periphery of the wafer W by the drying gas supplied from the sideof the rotational center Po, so that the wafer is dried. Therefore thewafer W can be efficiently dried

In a case where the fluid nozzle 12 is divided into a first fluid nozzleand a second fluid nozzle as described above, and a case where thesuction nozzle 80 shown in FIG. 8 is provided, these nozzles may beoptionally supported by separate arms. Alternatively, these nozzles maybe optionally moved in different directions.

Another embodiment of the substrate processing apparatus shown in FIG.11 is described below. In this embodiment, a humidity adjustor 85 isdisposed on a ceiling of a process vessel 2 as a humidity adjustingsystem that adjusts a humidity around a wafer W held by a spin chuck 3.The humidity adjustor 85 can adjust a humidity in an overall processingspace S in the process vessel 2. When carrying out at least one of theliquid film forming step and the drying step, the humidity in theprocess vessel 2 is lowered as compared with the humidity at thechemical process step and the rinsing step. In this case, it can beprevented that moisture contained in the processing space S is dissolvedin at least one of the first and second fluids supplied to the wafer W.Thus, the generation of particles on the wafer W after it is dried canbe prevented. In addition, drying of the wafer W can be expedited at thedrying step.

Another embodiment of the substrate processing apparatus provided with ahumidity adjusting system shown in FIG. 12 is described below. In thisembodiment, the humidity adjusting system 100 is constituted such that agas with an adjusted humidity is supplied into a processing space S in aprocess vessel 2 from above, and the gas is discharged from below.

To be specific, as shown in FIG. 12, the humidity adjusting system 100in this embodiment includes a gas supply vessel 91 that supplies intothe process vessel 2 an inert gas for adjusting a humidity. The gassupply vessel 91 is disposed on a ceiling of the process vessel 2. Abaffle plate 93 having a plurality of gas supply ports 94 is disposedbetween the gas supply vessel 91 and the process vessel 2. The gassupply ports 94 are uniformly distributed in the overall baffle plate93. The gas supply vessel 91 is connected to a gas supply source 96through a gas inlet channel 95. A humidity adjusting mechanism 92 isdisposed on the gas inlet channel 95 to adjust a humidity of an inertgas supplied from the gas supply source 96. The humidity adjustingmechanism 92 is controlled in accordance with a control instruction froma controller 16, and is capable of adjusting moisture contents containedin the inert gas to a given value. The inert gas supplied from the gassupply vessel 91 into the process vessel 2 downwardly flows into theprocess space S above the wafer W which is held by the spin chuck 3, andis discharged through an outlet port 98 formed in a bottom of theprocess vessel 2. Thus, a downflow of the inert gas with its humidityadjusted is formed in the processing space S, and thus the humidity inthe processing space S can be suitably controlled.

A gas for adjusting a humidity supplied from the gas supply source 96 isnot limited to an inert gas, and may be another gas such as an air. Whenair is used, the humidity in the processing space S can also befavorably controlled.

In general, a clean room in which a substrate processing apparatus isinstalled has a normal temperature (about 23° C.) and a relativehumidity of about 40% to about 45%. The humidity in the processing spaceS may be decreased in comparison with the relative humidity of the cleanroom, at least at one of the liquid film forming step and the dryingstep. This can further enhances a drying performance of the wafer W. Inthis case, the humidity of the processing space S may be, e.g., aboutnot more than 25% (relative humidity at a temperature of about 23° C.).Alternatively, the absolute humidity of the processing space S may be,e.g., about 5 g/m³.

Adjustment of the humidity in the processing space S is carried out atleast at only one of the film forming step and the drying step. However,not limited thereto, the humidity of the processing space S may beadjusted between the chemical process step and the rinsing step.Alternatively, the humidity of the processing space S may be constantlyadjusted.

The invention claimed is:
 1. A substrate processing apparatuscomprising: (a) a spin chuck configured to hold a substrate and rotatethe same; (b) a process liquid supply system configured to supply aprocess liquid to an upper surface of the substrate held by the spinchuck; (c) a fluid supply system having a fluid nozzle configured tosupply fluid to the upper surface of the substrate; (d) a nozzle movingmechanism configured to move radially outward the fluid nozzle relativeto a rotational center of the substrate; and (e) a controller configuredto control the spin chuck, the process liquid supply system, the fluidsupply system, and the nozzle moving mechanism, to cause: supplying ofthe process liquid from the process liquid supply system to the uppersurface of the substrate; thereafter, forming a liquid film by supplyinga first fluid, that has a higher volatility than that of the processliquid, from the fluid nozzle to the whole upper surface of thesubstrate such that the first fluid mixes with the process liquid toform the liquid film; and thereafter, supplying a second fluid, that hasa higher volatility than that of the process liquid, from the fluidnozzle to the upper surface of the substrate to the liquid film on thewhole upper surface of the substrate, while rotating the substrate bythe spin chuck and moving the fluid nozzle radially outward by thenozzle moving mechanism to flush away and remove the liquid film fromthe substrate.
 2. The substrate processing apparatus according to claim1, further comprising a drying gas nozzle configured to supply a dryinggas to the upper surface of the substrate; wherein the nozzle movingmechanism is configured to move radially outward the drying gas nozzleand the fluid nozzle relative to the rotational center of the substrate,while maintaining the drying gas nozzle nearer to the rotational centerof the substrate than the fluid nozzle.
 3. The substrate processingapparatus according to claim 2, wherein an opening dimension of thedrying gas nozzle is larger than an opening dimension of the fluidnozzle.
 4. The substrate processing apparatus according to claim 2,wherein the drying gas is an inert gas.
 5. The substrate processingapparatus according to claim 2, wherein the drying air is a dry air. 6.The substrate processing apparatus according to claim 2, furthercomprising a drying gas heater configured to heat the drying gas to besupplied from the drying gas nozzle.
 7. The substrate processingapparatus according to claim 1, further comprising a suction nozzleconfigured to suck an atmosphere near the upper surface of thesubstrate, wherein the nozzle moving mechanism is configured to move thesuction nozzle and the fluid nozzle radially outwardly relative to therotational center of the substrate, while maintaining the suction nozzlefarther away from the rotational center of the substrate than the fluidnozzle.
 8. The substrate processing apparatus according to claim 7,wherein the nozzle moving mechanism is configured to move the suctionnozzle and the fluid nozzle, while maintaining the suction nozzle aheadof the fluid nozzle, in a rotational direction of the substrate.
 9. Thesubstrate processing apparatus according to claim 1, further comprisinga humidity adjusting system configured to adjust a humidity around thesubstrate held by the spin chuck.
 10. The substrate processing apparatusaccording to claim 1, wherein the first fluid and the second fluid areidentical to each other.
 11. The substrate processing apparatusaccording to claim 1, wherein the process liquid is a deionized water.12. The substrate processing apparatus according to claim 1, wherein atleast one of the first fluid and the second fluid is selected from thegroup consisting of an IPA liquid, an IPA solution, a mist of IPAliquid, an IPA vapor, and a vapor of IPA solution.
 13. The substrateprocessing apparatus according to claim 1, further comprising a fluidheater configured to heat the second fluid to be supplied from the fluidnozzle.
 14. A substrate processing apparatus comprising: (a) a spinchuck configured to hold a substrate and rotate the same; (b) a processliquid supply system configured to supply a process liquid to an uppersurface of the substrate held by the spin chuck; (c) a fluid supplysystem having a fluid nozzle for a first fluid and a second fluid nozzlefor a second fluid configured to supply fluid to the upper surface ofthe substrate; (d) a nozzle moving mechanism configured to move thesecond fluid nozzle radially outward relative to a rotational center ofthe substrate; and (e) a controller configured to control the spinchuck, the process liquid supply system, the fluid supply system, andthe nozzle moving mechanism, to cause: supplying of the process liquidfrom the process liquid supply system to the upper surface of thesubstrate; thereafter, forming a liquid film by supplying the firstfluid, that has a higher volatility than that of the process liquid,from the first fluid nozzle to the whole upper surface of the substratesuch that the first fluid mixes with the process liquid to form theliquid film; and thereafter, supplying the second fluid, that has ahigher volatility than that of the process liquid, from the second fluidnozzle to the liquid film on the whole upper surface of the substrate,while rotating the substrate by the spin chuck and moving the secondfluid nozzle radially outward by the nozzle moving mechanism, to flushaway and remove the liquid film from the substrate.